Solved the problem with buy now form class

Fix for #795
Removed anonymous function

Fix for #795
PR for comment on issue #956

Based an additional comment on issue #956, the container will remain
VARIABLE unless the item is LARGE, in which case, the container will be
set as RECTANGULAR. A filter hook was added to allow the container
enumeration to be changed.
Merge pull request #967 from ReactorShop/master

PR for comment on issue #956
Merge pull request #938 from rubensargsyan/patch-2

Solved the problem with buy now form class
Merge branch 'master' of https://github.com/jbeales/WP-e-Commerce